GM's just revealed a whole messload of details on their newest members of the GMT-900-based full-size SUV and truck lineup — the 2009 Chevy Silverado XFE, 2009 Chevy Tahoe XFE, 2009 GMC Sierra XFE and lastly, the 2009 GMC Yukon XFE. What's XFE? It stands for Xtra Fuel Economy and the four relative fuel-sippers join the already class-leading Chevy Cobalt XFE as vehicles GMs achieved added wallet-padding using a combination of mechanical, aerodynamic and mass-reducing enhancements. The tweaks help to deliver a 5% increase in EPA-estimated highway fuel economy and more than 7% improved mileage in city driving. They achieve 15 city and 21 highway mileage ratings versus comparable non-XFE models' 14/20 ratings. The XFE designation is only available on 2WD vehicles equipped with the 5.3-liter V8 mated to a six-speed transmission. But we're told they're able to accomplish the fuel economy bump without a knock to towing ratings. The Tahoe and Yukon are unchanged, while the Silverado and Sierra increase from 6,600 pounds to 7,000 pounds due to the new, six-speed transmission and high-capacity cooling package. Still with us? Good. Hit the jump for our take.

Jalopnik Snap Judgment: This is a smart move by Chevy and GMC. If you give consumers some choice on fuel economy, more than likely they'll take it. Especially if it's at a low cost. That was the biggest problem we've got with the hybrid versions of GM's big SUVs — the added front end dollar figure destroys any possibility for recouping your monetary investment without driving the vehicle for tens of thousands of miles. But anyway, we're glad to see the General making any steps toward fuel economy gains at efficient prices — especially when mixed with the Tahoe's good looks — and without the garish stickering of the hybrid. Full press release below.

DETROIT - General Motors is building on the segment-leading fuel economy of its full-size pickups and SUVs with new XFE models of the 2009 Chevy Silverado, Chevy Tahoe, GMC Sierra and GMC Yukon. The vehicles use a combination of mechanical, aerodynamic and mass-reducing enhancements to deliver a 5-percent increase in EPA-estimated highway fuel economy and more than 7-percent improved mileage in city driving.

The aero enhancements make Silverado XFE and Sierra XFE models the most aerodynamic full-size pickups in the industry, with a "Best in Class" 0.412 coefficient of drag (cd). The pickups join the Tahoe Hybrid and Yukon Hybrid as the most aerodynamic full-size SUVs at 0.349 (cd).

The new XFE - Xtra Fuel Economy - models reflect GM's quick adaptation to an evolving market that remains a very important segment. They are available on 2WD vehicles equipped with the 5.3L V-8 and six-speed transmission. They achieve 15 city and 21 highway mileage ratings versus comparable non-XFE models' 14/20 ratings. Most importantly, the increased efficiency does not come at the expense of capability. Towing ratings for the Tahoe and Yukon are unchanged, while the Silverado and Sierra increase from 6,600 pounds (2,994 kg) to 7,000 pounds (3,175 kg) due to the new, six-speed transmission and high-capacity cooling package.

"We are pulling out all the stops to deliver a more efficient package for customers who need the capability of full-size pickups and SUVs and want the very best fuel economy," said Gary White, GM North America vice president and vehicle line executive for full-size trucks. "Our pickups and SUVs are already the fuel economy leaders of their respective segments, but our engineers knew greater efficiency was achievable. We fast-tracked the XFE models to get them into dealer showrooms as quickly as possible."

All models carry the XFE name badge and are offered in the LT trim for Silverado and LS and LT trims for Tahoe. Sierra XFE comes with SLE trim and Yukon XFE is offered with SLE and SLT trim. Most regular-production options for all models are available. Silverado XFE and Sierra XFE are offered in 2wd crew cab body styles only. Production begins this fall.

"In addition to the XFE models, GM already offers hybrid versions of the Tahoe and Yukon that achieve up to a 50-percent improvement in city fuel economy and coming in the first half of 2009 are the Silverado and Sierra Hybrids," said White. "These hybrid pickups offer up to 25 percent overall increased fuel economy and greater than 40-percent improved mileage in city driving."

XFE efficiencies

GM's more efficient full-size pickups and SUVs are powered by a 5.3L FlexFuel V-8 (LC9) engine that's built with a mass-reducing aluminum cylinder block and heads. It is rated at 320 horsepower (238 kW)* and 340 lb.-ft. of torque (461 Nm)* in Tahoe and Yukon and 315 hp/235 kW and 338 lb-ft/458 Nm in Silverado and Sierra. The engine is backed by a Hydra-Matic 6L80 six-speed automatic transmission (with high-capacity cooling on Silverado and Sierra).

A rear axle equipped with a fuel-saving 3.08 ratio is also standard on all XFE models. Lightweight aluminum wheels and low rolling resistance tires (with higher tire pressure) also are included on all models.

Other unique content and features for Silverado XFE and Sierra XFE include: